The polyphenylene sulfide (hereinafter abbreviated as “PPS”) resin has favorable properties as engineering plastic, for example, excellent heat resistance, chemical resistance, electrical insulation property and moist heat resistance. Accordingly, the PPS resin is used for various electric and electronic components, mechanical components and automobile components and more specifically for products produced by injection molding and extrusion molding.
In general, with a view to improving the rigidity and the heat resistance, a fibrous filler such as glass fibers having excellent reinforcing effect is often mixed with the PPS resin for injection molding. Mixing the PPS resin with the fibrous filler is, however, likely to cause (i) reduction of the flowability and thereby deterioration of the thin-wall moldability and is simultaneously likely to cause (ii) anisotropy by filler orientation. The PPS resin mixed with the fibrous filler thus often fails to meet the latest need for downsizing and light-weighting of automobile components and electric and electronic components. Addition of the fibrous filler to the PPS resin is likely to cause (iii) float of fillers to the surface of the molded product to form minute irregularities, and in fact has limitations in development of applications to especially automobile lighting components needing the high degree of surface smoothness. It is highly demanded to improve the characteristics of (i) to (iii) described above.
There have been reports with respect to the composition obtained by mixing mica with the PPS resin. For example, JP 2000-290504 A is an application describing a resin composition including a polyphenylene sulfide resin, potassium titanate fibers, carbon fibers and mica as a plate-like filler. JP '504, however, fails to teach that the heat resistance is improved by simply adding a relatively small amount of mica having the aspect ratio of not less than 80.
JP 2007-154167 A describes a resin composition including a polyphenylene sulfide resin, synthetic mica, calcium carbonate and a granular inorganic filler. It discloses the average particle diameter of the synthetic mica, but uses only mica having relatively small aspect ratios, for example, 25 or 2. JP '167 fails to teach that the heat resistance is improved by simply adding a relatively small amount of mica having the aspect ratio of not less than 80.
JP 2008-075049 A includes a polyphenylene sulfide resin, a copolymerized polyolefin, glass fibers and mica having the weight-average particle diameter of 10 to 100 μm. JP '049 similarly fails to teach that the heat resistance is improved by simply adding a relatively small amount of mica having the aspect ratio of not less than 80.
All of JP '504, JP '167 and JP '049 fail to teach that fine dispersion of at least one amorphous resin selected among polyether imide resins and polyether sulfone resins at a particle diameter of not greater than 1000 nm and control of the number of dispersed phases having the dispersed particle diameter of not less than 1000 nm to be not greater than 1.0% of the total number of dispersed phases improve the surface appearance and the impact resistance as well as the heat resistance and suppress warpage deformation.
It could therefore be helpful to provide a polyphenylene sulfide resin composition having excellent heat resistance, flowability and lightweight property, as well as surface smoothness and impact resistance, a production method thereof and a reflector with a metal layer formed on a molded product thereof.